This invention relates to carburetion systems for internal combustion engines and more particularly to a carburetion system in which adjustments in the delivery of fuel are made to compensate for changes in altitude.
With the present emphasis on fuel economy and reduced engine emissions for automobiles, numerous schemes have been developed for controlling the quantities of air and fuel mixed together and supplied to an automobile engine for combustion. A number of factors determine the correct proportions of air and fuel and one of these factors is the altitude at which an engine is operated. As an engine is operated at higher altitudes, less air is drawn into the engine and the resultant air-fuel mixture tends to become richer unless a correction is made in the quantity of fuel supplied to the engine. One way of compensating for altitude changes in a conventional carburetor is disclosed in U.S. Pat. No. 3,872,188 issued Mar. 18, 1975 to Brown et al and assigned to the same assignee as the present application. As shown in this patent, a capsule or bellows is responsive to changes in atmosphere to adjust the position of a metering pin and bleed more or less air into a carburetor fuel system, thereby controlling the quantity of fuel delivered to the engine. While such an apparatus does improve fuel economy and reduce emissions, the mechanical parts are subject to failure due to wear, engine vibrations, heat, etc. Further, other carburetion systems for an automobile engine do not function in the same manner as conventional carburetors but altitude compensation is still necessary to obtain the above stated goals.